New research suggests that the long-term neurologic symptoms, such as brain fog, that some patients with COVID-19 experience, may occur as a result of the occlusion of brain capillaries by large megakaryocytes.

The findings, shared in a research letter, report on five post-mortem cases from patients who succumbed to COVID-19. Researchers noted large cells that resembled megakaryocytes in cortical capillaries. Immunohistochemistry validated that they were megakaryocytes. According to the researchers, megakaryocytes have not been seen in the brain previously. The report is published online February 12 in JAMA Neurology.

Lead author David Nauen noted these cells in the first evaluation of brain tissue from a COVID-19 patient. He found no viral encephalitis, but there were unusually large cells in the brain capillaries. He stated that he had never seen these cells in the brain before… (Medscape)